The synthesis and crystal structure of the title trinuclear Mo cluster compound with somewhat loose coordination sites are reported. The compound is triclinic, space group P1, with a 10.472(4), b 14.375(2), c 21.695(3) ? a 74.04(1), b 76.50(2), and g 72.22(2)? d.(calcd.) = 1.693 for Z = 2. The atomic parameters are given. The structure was solved by the heavy-atom method and refined by full-matrix least-squares to R = 0.058. The distances between Mo atoms in this cluster are 2.731(1), 2.748(1), and 2.753(1) ? The mean value of Mo-Mo bond lengths is slightly shorter than those found in other trinuclear Mo clusters with a "loosely coordinated" site. In addition, the PPh3 ligand is loosely coordinated to 1 Mo atom in direction opposite to the m3-S atom with Mo-P bond length of 2.647(3) ? This differs from those of the other structurally analogous clusters, in which the loosely coordinated ligand is trans to m2-S atom. A review of Mo-Mo, Mo-L bonding for such clusters is given.

Key words: CRYSTAL STRUCTURE DETERMINATION, INFRARED SPECTROPHOTOMETRY, PROTON MAGNETIC RESONANCE SPECTROMETRY, MAGNETIC PERMEABILITY, MOLYBDENUM COMPLEX, TRIPHENYLPHOSPHINE, CHEMICAL BONDS, CLUSTER COMPOUND, PHOSPHORIC ACID ESTER, POLYNUCLEAR COMPLEX